What is the role of Tzanck smear in the workup of herpes zoster (shingles)?

Updated: Jan 25, 2019
  • Author: Camila K Janniger, MD; Chief Editor: Dirk M Elston, MD  more...
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Answer

Although varicella-zoster virus (VZV) can be cultured, its growth rate is usually too slow for culturing to make a timely contribution to diagnosis.

One of the least expensive and simplest laboratory diagnostic methods for VZV and other herpesviruses is the Tzanck smear. The Tzanck smear is performed by obtaining a scraping from the base of a fresh vesicular lesion after it has been unroofed, spreading and drying the collected material on a glass slide, staining the result with Giemsa, and examining the material with a microscope for the characteristic presence of multinucleated giant cells.

The Tzanck smear confirms that the lesion is herpetic but cannot differentiate between VZV and other herpesviruses. Further, this test has a limited sensitivity compared with other diagnostic methods, such as polymerase chain reaction (PCR) assay. Therefore, a negative result does not rule out a herpes virus infection and should not preclude empiric treatment in patients. [77]


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